We build a hi volume intake for stock frame TRX and for the 4 strokes as well. That is one of our best selling items. It optimizes the intake track length, and improves air flow. On the stock frame 250R intake we form a velocity stack shape after the straight section at the carburetor mouth and then use a cone to step up to a large mouth air filter. This shape gives us a large plenum area to hold filtered air and the divergence of cone broadens the power band. The cone shape helps us maximize the intake volume in the space we have and organizes the air so it is coming straight into the mouth of the carburetor. We always see hp gains with this design. The more hp the engine is making the higher the gains.